Like Polaris's similar courier bag, the Aquanought Backpack is a tough, welded-seam PVC bag that's 100% waterproof. It's even bigger, with a capacity of 30 litres and a couple of external shock cords that you could use to strap on a soggy commuter jacket or camper's sleeping mat.

Inside the bag there's just one cavernous compartment. It's as spacious as an Ortlieb Messengerbag although the shape is slightly different, more deep than wide. You won't get A3-sized items in here without bending, in the unlikely event you need to do so. The bonus is that the top corners of the bag aren't as prominent in your peripheral vision. And most loads will fit in fine.

There are a couple of clips inside the bag for attaching keys and the like, plus a generous outer pocket. This is big enough for a D-lock or a pair of shoes, so you can keep any oil or dirt of the main compartment's contents. It's sealed with a rainproof zip.

Bag stability is good when you're riding because the Aquanought Backpack has a sternum strap as well as a waist strap, and these and the shoulder straps are adjustable through a wide range. Even riding downhill on the drops on a fixed-wheel bike, the bag stayed put.

The shoulder straps and waist strap are wide and well padded, so the bag is pretty comfortable even when heavily loaded. There's a moulded EVA back panel to cushion the bag against your back. This panel is removable, as it attaches with swathes of Velcro to the back of the bag. I've no idea why you would want to remove this. Likewise, you can remove the Velcro-attached waist strap. I don't know why you'd want to do this either.

There are some channels in the EVA back panel to allow air to circulate a bit, but you will sweat all the same. It's an impermeable bag that covers most of your back.

The main compartment has a roll-top and buckle closure, which creates unnecessary faff if you're using this as an around-town or commuter bag. Ortlieb's Messengerbag and smaller, commuter-friendly Velocity use a roll-top with a simple Velcro strap. It works fine. The Aquanought's buckles fit into clasps on the end of long straps attached to the bottom corners of the bag. They can end up tangled in the waist strap, so you can't just toss something into the bag, jump on the bike and hit the road; you have to carefully strap the bag closed. If we're going to have buckles on the end of the roll-top at all, it would be quicker and simpler if the clasps were fixed to the sides of the bag, like an Ortlieb Front Roller City pannier.

There's a reflective patch for nighttime visibility, high up on the bag. This will be easier to see by following traffic the more upright you ride.

It's a tough, weatherproof bag that could be pressed into service for a range of uses – race kit bag, off-road backpack for bivvying or expeditions, and everyday commuter backpack. As a utility bag the faff with the roll-top straps wastes seconds, a minor annoyance that easier-access bags avoid.

It's available in white, black or bright green.

Verdict

A big, tough waterproof backpack with a faffy closure system.

road.cc test report

Make and model: Polaris Aquanought Backpack

Size tested: White

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

On Polaris's website, the backpack has icons for road, off-road and urban use. I'd agree with that - it's pretty versatile.

Tell us some more about the technical aspects of the product?

Polaris say:

- Fully waterproof backpack

- Welded seam technology

- 30 litre capacity

- Front waterproof pocket

- Elasticated shock cord for attachment of external items

- Reflective patch on rear

- Internal clips to attach accessories

- Full shoulder, chest and waist harness

- Removable EVA moulded back support for added comfort and stability

Rate the product for quality of construction:

8/10

Rate the product for performance:

7/10

Rate the product for durability:

9/10

Rate the product for weight, if applicable:

6/10

Rate the product for comfort, if applicable:

7/10

Like any big backpack, pretty sweaty.

Rate the product for value:

6/10

Tell us how the product performed overall when used for its designed purpose

It is completely waterproof and it's stable on your back, but I would prefer greater ease of access to the main compartment for utility use - which is what I think it will be used most for.

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